U.S. patent application number 14/270880 was filed with the patent office on 2014-11-13 for wire connection apparatus.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. The applicant listed for this patent is Samsung Electronics Co., Ltd.. Invention is credited to Byung June Choi, Yong Jae Kim, Young Do Kwon, Min Hyung Lee, Kyung Shik Roh, Young Bo Shim.
Application Number | 20140331798 14/270880 |
Document ID | / |
Family ID | 50630694 |
Filed Date | 2014-11-13 |
United States Patent
Application |
20140331798 |
Kind Code |
A1 |
Shim; Young Bo ; et
al. |
November 13, 2014 |
WIRE CONNECTION APPARATUS
Abstract
A wire connection apparatus includes a link unit and a drive
unit configured to drive the link unit. The link unit includes a
first link, a second link rotatably coupled to the first link, a
third link rotatably coupled to the second link, a plurality of
wires, each of which is fixed at one end thereof to the third link,
and is fixed at the other end thereof to the drive unit, and
through which a driving force is transmitted from the drive unit to
the third link, a path forming structure to form a path of each of
the wires between the drive unit and the third link, and a length
holding structure to hold constant a length of each of the wires
between the drive unit and the third link.
Inventors: |
Shim; Young Bo; (Seoul,
KR) ; Kwon; Young Do; (Yongin-si, KR) ; Choi;
Byung June; (Gunpo-si, KR) ; Kim; Yong Jae;
(Seoul, KR) ; Roh; Kyung Shik; (Seongnam-si,
KR) ; Lee; Min Hyung; (Anyang-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., Ltd. |
Suwon-si |
|
KR |
|
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
|
Family ID: |
50630694 |
Appl. No.: |
14/270880 |
Filed: |
May 6, 2014 |
Current U.S.
Class: |
74/89.22 |
Current CPC
Class: |
B25J 9/104 20130101;
Y10T 74/18848 20150115; F16H 2019/085 20130101; F16H 19/08
20130101 |
Class at
Publication: |
74/89.22 |
International
Class: |
F16H 19/08 20060101
F16H019/08 |
Foreign Application Data
Date |
Code |
Application Number |
May 7, 2013 |
KR |
10-2013-0051483 |
Claims
1. A wire connection apparatus comprising: a link unit; and a drive
unit configured to drive the link unit; wherein the link unit
comprises: a first link; a second link rotatably coupled to the
first link; a third link rotatably coupled to the second link; a
plurality of wires, each of which is fixed at one end thereof to
the third link, and is fixed at the other end thereof to the drive
unit, and through which a driving force is transmitted from the
drive unit to the third link; a path forming structure to form a
path of each of the wires between the drive unit and the third
link; and a length holding structure to hold constant a length of
each of the wires between the drive unit and the third link.
2. The wire connection apparatus of claim 1, wherein the first link
comprises a first rotation shaft and a second rotation shaft that
are spaced apart from each other; the second link is rotatably
coupled to the first rotation shaft; and the path forming structure
comprises: a first pulley rotatably coupled to the first rotation
shaft; a second pulley rotatably coupled to the second rotation
shaft; a third pulley rotatably coupled to the second rotation
shaft; and a plurality of fourth pulleys rotatably coupled to the
second pulley.
3. The wire connection apparatus of claim 2, wherein the plurality
of wires are wound around the first pulley, the second pulley, the
fourth pulleys, and the third pulley in serial order from the third
link to the drive unit.
4. The wire connection apparatus of claim 3, wherein the plurality
of wires comprise a first wire and a second wire; and the first
wire is wound around the first pulley in a first direction, wound
around the second pulley and the fourth pulleys in a second
direction opposite to the first direction, and wound around the
third pulley in the first direction.
5. The wire connection apparatus of claim 4, wherein the second
wire is wound around each of the first pulley, the second pulley,
the fourth pulleys, and the third pulley in a direction opposite to
the direction in which the first wire is wound around each of the
first pulley, the second pulley, the fourth pulleys, and the third
pulley.
6. The wire connection apparatus of claim 2, wherein the length
holding structure comprises: a first interlocking gear arranged in
the second link; and a second interlocking gear arranged in the
second pulley to engage with the first interlocking gear.
7. The wire connection apparatus of claim 6, wherein the second
interlocking gear is configured to rotate in a direction opposite
to the second link.
8. The wire connection apparatus of claim 2, wherein a sum of a
radius of the first pulley and a radius of the second pulley is
equal to a length of a straight line between a center of rotation
of the first pulley and a center of rotation of the second
pulley.
9. The wire connection apparatus of claim 2, wherein a sum of a
radius of the third pulley and a diameter of each of the fourth
pulleys is equal to a radius of the second pulley.
10. The wire connection apparatus of claim 2, wherein the fourth
pulleys are a pair of fourth pulleys; and the pair of fourth
pulleys are symmetrically arranged with respect to a straight line
joining a center of rotation of the first pulley and a center of
rotation of the second pulley.
11. The wire connection apparatus of claim 2, wherein the plurality
of wires comprise a pair of first wires and a pair of second wires;
and the wire connection apparatus further comprises: a first
divergence roller disposed between the third link and the first
pulley to diverge the pair of first wires from each other; a second
divergence roller disposed between the third link and the first
pulley to diverge the pair of second wires from each other; a first
coupling roller disposed between the third pulley and the drive
unit to couple together the pair of first wires that are diverged
from each other; and a second coupling roller disposed between the
third pulley and the drive unit to couple together the pair of
second wires that are diverged from each other; wherein the pair of
first wires and the pair of second wires are wound around the first
pulley, the second pulley, the fourth pulleys, and the third pulley
in directions opposite to each other.
12. A wire connection apparatus comprising: a link unit; and a
drive unit configured to drive the link unit; wherein the link unit
comprises: a first link; a second link rotatably coupled to the
first link; a third link rotatably coupled to the second link; a
first pulley configured to freely rotate about a same axis as the
second link; a second pulley configured to interlock with the
second link and rotate as the second link rotates; a third pulley
configured to freely rotate about a same axis as the second pulley;
a plurality of fourth pulleys coupled to the second pulley and
configured to freely rotate; and a plurality of wires connected
from the third link to the drive unit via, in serial order, the
first pulley, the second pulley, the fourth pulleys, and the third
pulley.
13. The wire connection apparatus of claim 12, wherein the
plurality of wires comprise a first wire and a second wire; the
first wire is wound around the first pulley in a first direction,
wound around the second pulley and a first one of the fourth
pulleys in a second direction opposite to the first direction, and
wound around the third pulley in the first direction; and the
second wire is wound around each of the first pulley, the second
pulley, a second one of the fourth pulleys, and the third pulley in
a direction opposite to the direction in which the first wire is
wound around each of the first pulley, the second pulley, the first
one of the fourth pulleys, and the third pulley.
14. The wire connection apparatus of claim 13, further comprising:
a first interlocking gear arranged in the second link; and a second
interlocking gear arranged in the second pulley to engage with the
first interlocking gear.
15. The wire connection apparatus of claim 14, wherein the second
pulley is configured to rotate in the second direction as the
second link rotates in the first direction to hold constant
respective lengths of the first wire and the second wire between
the third link and the drive unit; and the second pulley is further
configured to rotate in the first direction as the second link
rotates in the second to hold constant the respective lengths of
the first wire and the second wire between the third link and the
drive unit.
16. The wire connection apparatus of claim 12, wherein the
plurality of wires comprise a pair of first wires and a pair of
second wires; and the wire connection apparatus further comprises:
a first divergence roller disposed between the third link and the
first pulley to diverge the pair of first wires from each other; a
second divergence roller disposed between the third link and the
first pulley to diverge the pair of second wires from each other; a
first coupling roller disposed between the third pulley and the
drive unit to couple the pair of first wires that are diverged from
each other; and a second coupling roller disposed between the third
pulley and the drive unit to couple the pair of second wires that
are diverged from each other.
17. A wire connection apparatus comprising: a base link; a middle
link rotatably coupled to the base link and configured to rotate
relative to the base link without changing an axis of rotation of
the middle link; an end effecter rotatably coupled to the middle
link; and at least one wire traversing a path along the base link
and the middle link from a reference point and fixed to the end
effecter; wherein a length of the at least one wire from the
reference point to the end effecter is held constant even when the
middle link rotates.
18. The wire connection apparatus of claim 17, further comprising a
drive unit; wherein the reference point is a portion of the drive
unit.
19. The wire connection apparatus of claim 17, wherein the at least
one wire comprises: a first wire traversing a first path between
the reference point and the end effecter; and a second wire
traversing a second path different from the first path between the
reference point and the end effecter.
20. The wire connection apparatus of claim 17, wherein the at least
one wire comprises a pair of wires that are diverged from each
other in at least a partial section of the connection apparatus
between the reference point and the end effecter.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Korean Patent
Application No. 10-2013-0051483 filed on May 7, 2013 in the Korean
Intellectual Property Office, the entire disclosure of which is
incorporated herein by reference for all purposes.
BACKGROUND
[0002] 1. Field
[0003] This application relates to a wire connection apparatus to
drive links using wires.
[0004] 2. Description of Related Art
[0005] There is a drive structure using wires as a structure that
allows a mechanism configured by a plurality of links to be driven.
In the drive structure using the wires, a driver is not directly
connected to an end effecter or an articulated joint through which
one link is joined to another link, but is located at a part that
has no motion or little motion, so the link may be minimized in
weight, size, and inertia. Therefore, an advantageous design is
possible in terms of driving efficiency and stability of a
robot.
[0006] In the drive structure using the wires, the wires are
typically connected to the driver via a plurality of moving links.
In this case, a length of a path of each wire varies according to a
motion of a link between the end effecter and the driver and a
motion of the articulated joint through which one link is joined to
another link, thereby resulting in a coupled motion of the end
effecter. That is, the motion of the link or the articulated joint
will cause the end effecter to move even if the driver is in a
fixed state.
SUMMARY
[0007] This Summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the Detailed Description. This Summary is not intended to identify
key features or essential features of the claimed subject matter,
nor is it intended to be used as an aid in determining the scope of
the claimed subject matter.
[0008] In one general aspect, a wire connection apparatus includes
a link unit; and a drive unit configured to drive the link unit;
wherein the link unit includes a first link; a second link
rotatably coupled to the first link; a third link rotatably coupled
to the second link; a plurality of wires, each of which is fixed at
one end thereof to the third link, and is fixed at the other end
thereof to the drive unit, and through which a driving force is
transmitted from the drive unit to the third link; a path forming
structure to form a path of each of the wires between the drive
unit and the third link; and a length holding structure to hold
constant a length of each of the wires between the drive unit and
the third link.
[0009] The first link may include a first rotation shaft and a
second rotation shaft that are spaced apart from each other; the
second link may be rotatably coupled to the first rotation shaft;
and the path forming structure may include a first pulley rotatably
coupled to the first rotation shaft; a second pulley rotatably
coupled to the second rotation shaft; a third pulley rotatably
coupled to the second rotation shaft; and a plurality of fourth
pulleys rotatably coupled to the second pulley.
[0010] The plurality of wires may be wound around the first pulley,
the second pulley, the fourth pulleys, and the third pulley in
serial order from the third link to the drive unit.
[0011] The plurality of wires may include a first wire and a second
wire; and the first wire may be wound around the first pulley in a
first direction, wound around the second pulley and the fourth
pulleys in a second direction opposite to the first direction, and
wound around the third pulley in the first direction.
[0012] The second wire may be wound around each of the first
pulley, the second pulley, the fourth pulleys, and the third pulley
in a direction opposite to the direction in which the first wire is
wound around each of the first pulley, the second pulley, the
fourth pulleys, and the third pulley.
[0013] The length holding structure may include a first
interlocking gear arranged in the second link; and a second
interlocking gear arranged in the second pulley to engage with the
first interlocking gear.
[0014] The second interlocking gear may be configured to rotate in
a direction opposite to the second link.
[0015] A sum of a radius of the first pulley and a radius of the
second pulley may be equal to a length of a straight line between a
center of rotation of the first pulley and a center of rotation of
the second pulley.
[0016] A sum of a radius of the third pulley and a diameter of each
of the fourth pulleys may be equal to a radius of the second
pulley.
[0017] The fourth pulleys may be a pair of fourth pulleys; and the
pair of fourth pulleys may be symmetrically arranged with respect
to a straight line joining a center of rotation of the first pulley
and a center of rotation of the second pulley.
[0018] The plurality of wires may include a pair of first wires and
a pair of second wires; the wire connection apparatus may further
include a first divergence roller disposed between the third link
and the first pulley to diverge the pair of first wires from each
other; a second divergence roller disposed between the third link
and the first pulley to diverge the pair of second wires from each
other; a first coupling roller disposed between the third pulley
and the drive unit to couple together the pair of first wires that
are diverged from each other; and a second coupling roller disposed
between the third pulley and the drive unit to couple together the
pair of second wires that are diverged from each other; and the
pair of first wires and the pair of second wires may be wound
around the first pulley, the second pulley, the fourth pulleys, and
the third pulley in directions opposite to each other.
[0019] In another general aspect, a wire connection apparatus
includes a link unit; and a drive unit configured to drive the link
unit; wherein the link unit may include a first link; a second link
rotatably coupled to the first link; a third link rotatably coupled
to the second link; a first pulley configured to freely rotate
about a same axis as the second link; a second pulley configured to
interlock with the second link and rotate as the second link
rotates; a third pulley configured to freely rotate about a same
axis as the second pulley; a plurality of fourth pulleys coupled to
the second pulley and configured to freely rotate; and a plurality
of wires connected from the third link to the drive unit via, in
serial order, the first pulley, the second pulley, the fourth
pulleys, and the third pulley.
[0020] The plurality of wires may include a first wire and a second
wire; the first wire may be wound around the first pulley in a
first direction, wound around the second pulley and a first one of
the fourth pulleys in a second direction opposite to the first
direction, and wound around the third pulley in the first
direction; and the second wire may be wound around each of the
first pulley, the second pulley, a second one of the fourth
pulleys, and the third pulley in a direction opposite to the
direction in which the first wire is wound around each of the first
pulley, the second pulley, the first one of the fourth pulleys, and
the third pulley.
[0021] The wire connection apparatus may further include a first
interlocking gear arranged in the second link; and a second
interlocking gear arranged in the second pulley to engage with the
first interlocking gear.
[0022] The second pulley may be configured to rotate in the second
direction as the second link rotates in the first direction to hold
constant respective lengths of the first wire and the second wire
between the third link and the drive unit; and the second pulley
may be further configured to rotate in the first direction as the
second link rotates in the second to hold constant the respective
lengths of the first wire and the second wire between the third
link and the drive unit.
[0023] The plurality of wires may include a pair of first wires and
a pair of second wires; and the wire connection apparatus may
further include a first divergence roller disposed between the
third link and the first pulley to diverge the pair of first wires
from each other; a second divergence roller disposed between the
third link and the first pulley to diverge the pair of second wires
from each other; a first coupling roller disposed between the third
pulley and the drive unit to couple the pair of first wires that
are diverged from each other; and a second coupling roller disposed
between the third pulley and the drive unit to couple the pair of
second wires that are diverged from each other.
[0024] In another general aspect, a wire connection apparatus
includes a base link; a middle link rotatably coupled to the base
link and configured to rotate relative to the base link without
changing an axis of rotation of the middle link; an end effecter
rotatably coupled to the middle link; and at least one wire
traversing a path along the base link and the middle link from a
reference point and fixed to the end effecter; wherein a length of
the at least one wire from the reference point to the end effecter
is held constant even when the middle link rotates.
[0025] The wire connection apparatus may further include a drive
unit; and the reference point may be a portion of the drive
unit.
[0026] The at least one wire may include a first wire traversing a
first path between the reference point and the end effecter; and a
second wire traversing a second path different from the first path
between the reference point and the end effecter.
[0027] The at least one wire may include a pair of wires that are
diverged from each other in at least a partial section of the
connection apparatus between the reference point and the end
effecter.
[0028] In another general aspect, a wire connection apparatus
includes a base link; a middle link rotatably coupled to the base
link and configured to rotate relative to the base link about an
axis of rotation that is fixed relative to the base link; an end
effecter rotatably coupled to the middle link; at least one wire
fixed to the end effecter and traversing a path from the end
effecter to at least one reference point along the middle link and
the base link; and a path forming structure configured to hold
constant a length of the at least one wire from the reference point
to the end effecter as the middle link rotates without diverging
the at least one wire from the middle link and the base link.
[0029] The path forming structure may prevent the end effecter from
moving relative to the middle link as the middle link rotates when
a driving force is not applied to the end effecter.
[0030] The reference point may include a first reference point and
a second reference point different from the first reference point;
and the at least one wire may include a first wire traversing a
first path from the end effecter to the first reference point; and
a second wire traversing a second path from the end effecter to the
second reference point.
[0031] The at least one wire may include a first wire traversing a
first path from the end effecter to the reference point; and a
second wire traversing a second path different from the first path
from the end effecter to the reference point.
[0032] The first wire and the second wire may traverse a same path
in a portion of the first path and a portion of the second path;
and the first wire and the second wire may traverse different paths
in another portion of the first path and another portion of the
second path.
[0033] Other features and aspects will be apparent from the
following detailed description, the drawings, and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 illustrates an example of a link unit and a drive
unit.
[0035] FIGS. 2A and 2B illustrate examples of a state in which the
link unit is driven and operated.
[0036] FIG. 3 is a diagram for explaining a rotation ratio between
a first interlocking gear and a second interlocking gear to hold
constant lengths of a first wire and a second wire constant.
[0037] FIGS. 4A and 4B illustrate another example of a link unit
and a drive unit, and illustrate an example of a structure that
forms paths of a pair of first wires and a pair of second
wires.
[0038] FIGS. 5A and 5B are diagrams for explaining a principle by
which a difference in tensions applied to the first wires and the
second wires is offset.
DETAILED DESCRIPTION
[0039] This Summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the Detailed Description. This Summary is not intended to identify
key features or essential features of the claimed subject matter,
nor is it intended to be used as an aid in determining the scope of
the claimed subject matter.
[0040] Throughout the drawings and the detailed description, the
same reference numerals refer to the same elements. The drawings
may not be to scale, and the relative size, proportions, and
depiction of elements in the drawings may be exaggerated for
clarity, illustration, and convenience.
[0041] In this application, for convenience of description, a first
direction A refers to a clockwise direction, and a second direction
B refers to a counterclockwise direction.
[0042] FIG. 1 illustrates an example of a link unit and a drive
unit. FIGS. 2A and 2B illustrate examples of a state in which the
link unit is driven and operated.
[0043] As shown in FIGS. 1 to 2B, a wire connection apparatus 10
includes a link unit 100 and a drive unit 200 to drive the link
unit 100.
[0044] The link unit 100 includes a plurality of links 110, 120,
and 130 arranged in a line, a plurality of wires 140 and 150
through which a driving force of the drive unit 200 is transmitted
to the link 130 constituting an end effecter 130, a path forming
structure 160 to form paths of the wires 140 and 150 between the
drive unit 200 and the end effecter 130, and a length holding
structure 170 to hold constant lengths of the wires 140 and 150
between the drive unit 200 and the end effecter 130.
[0045] The plurality of links 110, 120, and 130 include a base link
110, a middle link 120 rotatably coupled to the base link 110, and
an end effecter 130 rotatably coupled to the middle link 120.
[0046] The base link 110 includes a first rotation shaft 112
rotatably coupled with the middle link 120 and a first pulley 162
that will be described later, and a second rotation shaft 114
rotatably coupled to a second pulley 164 and a third pulley 166
that will be described later. The first and second rotation shafts
112 and 114 protrude from one side of the base link 110 and are
spaced apart from each other on the one side of the base link
110.
[0047] The middle link 120 includes a third rotation shaft 122
rotatably coupled with the end effecter 130.
[0048] The end effecter 130 is provided with a first wire fixing
portion 132 and a second wire fixing portion 134 to which
respective ends of the wires 140 and 150 are fixed.
[0049] The end effecter 130 is not limited to being a link located
at an end or a tip of the link unit 100 only, but may be a link
between the links or another middle link. Accordingly, for
convenience of description below, the base link 110, the middle
link 120, and the end effecter 130 will be referred to as a first
link 110, a second link 120, and a third link 130 in order of
increasing distance from the drive unit 200.
[0050] The wires 140 and 150 include a first wire 140 and a second
wire 150 to rotate the third link 130.
[0051] One end 142 of the first wire 140 is fixed to the first wire
fixing portion 132 of the third link 130, and the other end 144 of
the first wire 140 is fixed to a third wire fixing portion 212 of
the drive unit 200, which is a reference point measuring the length
of the wire 140.
[0052] Similarly, one end 152 of the second wire 150 is fixed to
the second wire fixing portion 134 of the third link 130, and the
other end 154 of the second wire 150 is fixed to a fourth wire
fixing portion 214 of the drive unit 200, which is a reference
point measuring the length of the wire 150.
[0053] The second and third links 120 and 130 rotate in the first
direction A or the second direction B opposite to the first
direction A due to a difference in tensions applied to the first
and second wires 140 and 150.
[0054] The path forming structure 160 includes the first pulley 162
rotatably coupled to the first rotation shaft 112, the second
pulley 164 rotatably coupled to the second rotation shaft 114, the
third pulley 166 rotatably coupled to the second rotation shaft 114
and spaced apart from the second pulley 164 in an axial direction
of the second rotation shaft 114, and a pair of fourth pulleys 168a
and 168b rotatably coupled to the second pulley 164.
[0055] The first pulley 162 is coupled to the first rotation shaft
112 so as to freely rotate about the first rotation shaft 112. The
first and second wires 140 and 150 are wound around the first
pulley 162 in opposite directions to each other. In the examples of
FIGS. 2A and 2B, the first wire 140 is wound around the first
pulley 162 in the first direction A when viewed from the first wire
fixing portion 132, and the second wire 150 is wound around the
first pulley 162 in the second direction B when viewed from the
second wire fixing portion 134.
[0056] The second pulley 164 interlocks with the second link 120
and rotates by the action of the length holding structure 170 that
will be described later, and includes a pair of fourth rotation
shafts 164a and 164b rotatably coupled with the pair of fourth
pulleys 168a and 168b. The first and second wires 140 and 150 are
wound around the second pulley 164 in opposite directions to each
other. In the examples of FIGS. 2A and 2B, the first wire 140 is
wound around the second pulley 164 in the second direction B when
viewed from the first wire fixing portion 132, and the second wire
150 is wound around the second pulley 164 in the first direction A
when viewed from the second wire fixing portion 134.
[0057] The first and second pulleys 162 and 164 may be arranged
such that a sum of a radius R1 of the first pulley 162 and a radius
R2 of the second pulley 164 is equal to a length of a straight line
L1 between a center of rotation C1 of the first pulley 162 and a
center of rotation C2 of the second pulley 164.
[0058] The third pulley 166 is coupled to the second rotation shaft
114 so as to freely rotate about the second rotation shaft 114. The
first and second wires 140 and 150 are wound around the third
pulley 166 in opposite directions to each other. In the examples of
FIGS. 2A and 2B, the first wire 140 is wound around the third
pulley 166 in the first direction A when viewed from the first wire
fixing portion 132, and the second wire 150 is wound around the
third pulley 166 in the second direction B when viewed from the
second wire fixing portion 134.
[0059] The pair of fourth pulleys 168a and 168b are coupled to the
pair of fourth rotation shaft 164a and 164b, respectively, so as to
freely rotate about the pair of fourth rotation shaft 164a and
164b, respectively. The first and second wires 140 and 150 are
wound around the fourth pulleys 168a and 168b, respectively, in
opposite directions to each other. In the examples of FIGS. 2A and
2B, the first wire 140 is wound around the pulley 168b of the pair
of fourth pulleys 168a and 168b in the second direction B when
viewed from the first wire fixing portion 132, and the second wire
150 is wound around the fourth pulley 168a in the first direction A
when viewed from the second wire fixing portion 134.
[0060] The third pulley 166 and the pair of fourth pulleys 168a and
168b may be arranged such that a sum of a radius R3 of the third
pulley 166 and a diameter 2.times.R4 of each of the pair of fourth
pulleys 168a and 168b is equal to a radius R2 of the second pulley
164.
[0061] In addition, the pair of fourth pulleys 168a and 168b may be
symmetrically arranged with respect to the straight line L1 joining
the center of rotation C1 of the first pulley 162 and the center of
rotation C2 of the second pulley 164.
[0062] To summarize the paths of the first and second wires 140 and
150 defined by the above-mentioned path forming structure 160, the
first wire 140 is fixed to the first wire fixing portion 132, moves
along the second link 120, is wound around the first pulley 162 in
the first direction A, is wound around the second and fourth
pulleys 164 and 168b in the second direction B, is wound around the
third pulley 166 in the first direction A, and is then fixed to the
third wire fixing portion 212. The second wire 150 is fixed to the
second wire fixing portion 134, moves along the second link 120, is
wound around the first pulley 162 in the second direction B, is
wound around the second and fourth pulleys 164 and 168a in the
first direction A, is wound around the third pulley 166 in the
second direction B, and is then fixed to the fourth wire fixing
portion 214.
[0063] The length holding structure 170 includes a first
interlocking gear 172 arranged in the second link 120 and a second
interlocking gear 174 arranged in the second pulley 164 to engage
with the first interlocking gear 172. The first interlocking gear
172 may be formed integrally with the second link 120, and the
second interlocking gear 174 may be formed integrally with the
second pulley 164.
[0064] The second interlocking gear 174 allows the second pulley
164 to rotate in a direction opposite to the rotation direction of
the second link 120 during rotation of the second link 120 relative
to the first link 110, with the consequence that the length of the
first wire 140 between the first wire fixing portion 132 and the
third wire fixing portion 212 and the length of the second wire 150
between the second wire fixing portion 134 and the fourth wire
fixing portion 214 are held constant.
[0065] As shown in FIG. 2A, when the second interlocking gear 174
engaging with the first interlocking gear 172 and the second pulley
164 rotate in the second direction B as the second link 120 and the
first interlocking gear 172 rotate in the first direction A, the
length of the first wire 140 between the first wire fixing portion
132 and the third wire fixing portion 212 and the length of the
second wire 150 between the second wire fixing portion 134 and the
fourth wire fixing portion 214 are held constant.
[0066] The length of the first wire 140 from the first wire fixing
portion 132 to a point K at which the first wire 140 is decoupled
from the second link 120 and begins to be wound around the second
pulley 164 by rotation of the second link 120 and the first
interlocking gear 172 in the first direction A is decreased,
compared with a state in which the second link 120 and the first
link 110 are arranged in a straight line as shown in FIG. 1. In
this case, however, the length of the first wire 140 to the third
wire fixing portion 212 from the point K at which the first wire
140 is decoupled from the second link 120 and begins to be wound
around the second pulley 164 by rotation of the second pulley 164
in the second direction B is increased, thereby offsetting the
decreased length of the first wire 140 from the first wire fixing
portion 132 to the point K at which the first wire 140 is decoupled
from the second link 120 and begins to be wound around the second
pulley 164. Consequently, the length of the first wire 140 between
the first wire fixing portion 132 and the third wire fixing portion
212 is always held constant.
[0067] In addition, the length of the second wire 150 from the
second wire fixing portion 134 to a point K at which the second
wire 150 is decoupled from the second link 120 and begins to be
wound around the second pulley 164 by rotation of the second link
120 and the first interlocking gear 172 in the first direction A is
increased, compared with a state in which the second link 120 and
the first link 110 are arranged in a straight line as shown in FIG.
1. In this case, however, the length of the second wire 150 to the
fourth wire fixing portion 214 from the point K at which the second
wire 150 is decoupled from the second link 120 and begins to be
wound around the second pulley 164 by rotation of the second pulley
164 in the second direction B is decreased, thereby offsetting the
increased length of the second wire 150 from the second wire fixing
portion 134 to the point K at which the second wire 150 is
decoupled from the second link 120 and begins to be wound around
the second pulley 164. Consequently, the length of the second wire
150 between the second wire fixing portion 134 and the fourth wire
fixing portion 214 is always held constant.
[0068] As shown in FIG. 2B, when the second interlocking gear 174
engaging with the first interlocking gear 172 and the second pulley
164 rotate in the first direction A as the second link 120 and the
first interlocking gear 172 rotate in the second direction B, the
length of the first wire 140 between the first wire fixing portion
132 and the third wire fixing portion 212 and the length of the
second wire 150 between the second wire fixing portion 134 and the
fourth wire fixing portion 214 are held constant.
[0069] The length of the first wire 140 from the first wire fixing
portion 132 to the point K at which the first wire 140 is decoupled
from the second link 120 and begins to be wound around the second
pulley 164 by rotation of the second link 120 and the first
interlocking gear 172 in the second direction B is increased,
compared with a state in which the second link 120 and the first
link 110 are arranged in a straight line as shown in FIG. 1. In
this case, however, the length of the first wire 140 to the third
wire fixing portion 212 from the point K at which the first wire
140 is decoupled from the second link 120 and begins to be wound
around the second pulley 164 by rotation of the second pulley 164
in the first direction A is decreased, thereby offsetting the
increased length of the first wire 140 from the first wire fixing
portion 132 to the point K at which the first wire 140 is decoupled
from the second link 120 and begins to be wound around the second
pulley 164. Consequently, the length of the first wire 140 between
the first wire fixing portion 132 and the third wire fixing portion
212 is always held constant.
[0070] In addition, the length of the second wire 150 from the
second wire fixing portion 134 to the point K at which the second
wire 150 is decoupled from the second link 120 and begins to be
wound around the second pulley 164 by rotation of the second link
120 and the first interlocking gear 172 in the second direction B
is decreased, compared with a state in which the second link 120
and the first link 110 are arranged in a straight line as shown in
FIG. 1. In this case, however, the length of the second wire 150 to
the fourth wire fixing portion 214 from the point K at which the
second wire 150 is decoupled from the second link 120 and begins to
be wound around the second pulley 164 by rotation of the second
pulley 164 in the first direction A is increased, thereby
offsetting the decreased length of the second wire 150 from the
second wire fixing portion 134 to the point K at which the second
wire 150 is decoupled from the second link 120 and begins to be
wound around the second pulley 164. Consequently, the length of the
second wire 150 between the second wire fixing portion 134 and the
fourth wire fixing portion 214 is always held constant.
[0071] FIG. 3 is a diagram for explaining a rotation ratio between
the first interlocking gear and the second interlocking gear to
hold constant the lengths of the wires 140 and 150 constant.
[0072] As shown in FIG. 3, assuming that the length of the first
wire 140 between the first wire fixing portion 132 and the third
wire fixing portion 212 is held constant when the second link 120
and the first interlocking gear 172 rotate in the first direction A
by .theta.a.degree. and the second pulley 164 interlocks with the
second link 120 and the first interlocking gear 172 and rotates in
the second direction B by .theta.b.degree., the decreased length La
of the first wire 140 from the first wire fixing portion 132 to the
point K at which the first wire 140 is decoupled from the second
link 120 and begins to be wound around the second pulley 164 is
expressed by the following Equation 1.
La=R1.times..theta.a (1)
[0073] Meanwhile, the increased length Lb of the first wire 140 to
the third wire fixing portion 212 from the point K at which the
first wire 140 is decoupled from the second link 120 and begins to
be wound around the second pulley 164 is expressed by the following
Equation 2.
Lb=(R2.times..theta.b)+(R3.times..theta.b) (2)
[0074] In addition, since the sum of the radius R3 of the third
pulley 166 and the diameter 2.times.R4 of each of the pair of
fourth pulleys 168a and 168b is equal to the radius R2 of the
second pulley 164, the following Equation 3 may be established.
R2=R3+(2.times.R4) (3)
[0075] The following Equation 4 is obtained by substituting
Equation (3) into Equation (2).
Lb=2.times..theta.b.times.(R3+R4) (4)
[0076] Since the decreased length La of the first wire 140 from the
first wire fixing portion 132 to the point K at which the first
wire 140 is decoupled from the second link 120 and begins to be
wound around the second pulley 164 is equal to the increased length
Lb of the first wire 140 to the third wire fixing portion 212 from
the point K at which the first wire 140 is decoupled from the
second link 120 and begins to be wound around the second pulley
164, the following Equation 5 is satisfied.
R1.times..theta.a=2.times..theta.b.times.(R3+R4) (5)
[0077] The following Equation 6 is obtained by rearranging Equation
(5).
.theta.a/.theta.b=2.times.(R3+R4)/R1 (6)
[0078] Accordingly, the rotation ratio between the first
interlocking gear 172 and the second interlocking gear 174 to hold
constant the length of the first wire 140 constant is expressed by
the following Equation 7.
.theta.a:.theta.b=2.times.(R3+R4):R1 (7)
[0079] The rotation ratio between the first interlocking gear 172
and the second interlocking gear 174 to hold constant the length of
the second wire 150 is the same as described above, so no detailed
description will be provided.
[0080] As described above, since the length of the first wire 140
between the first wire fixing portion 132 and the third wire fixing
portion 212 and the length of the second wire 150 between the
second wire fixing portion 134 and the fourth wire fixing portion
214 by interlocking of the first and second interlocking gears 172
and 174 are always held constant during rotation of the second link
120 in the first direction A or the second direction B, the third
link 130 is prevented from rotating relative to the second link 120
in an unwanted direction.
[0081] Another example will now be described. No description will
be provided of the same parts as example described above.
[0082] FIGS. 4A and 4B are diagrams illustrating a link unit and a
drive unit according to another example, and illustrating a
structure forming paths of a pair of first wires and a pair of
second wires.
[0083] Although the pair of first wires 140a and 140b and the pair
of second wires 150a and 150b are included in the same link unit
and are simultaneously operated, the first wires 140a are shown in
FIG. 4A and the second wires 140b are shown in FIG. 4B for
convenience of description.
[0084] As shown in FIGS. 4A and 4B, the wires 140a, 140b, 150a, and
150b include a pair of first wires 140a and 140b and a pair of
second wires 150a and 150b. The link unit 100 further includes a
first divergence roller 182 disposed between the third link 130 and
the first pulley 162 to diverge the pair of first wires 140a and
140b, a second divergence roller 184 spaced apart from the first
divergence roller 182 and disposed between the third link 130 and
the first pulley 162 to diverge the pair of second wires 150a and
150b, a first coupling roller 192 disposed between the third pulley
166 and the drive unit 200 to couple the pair of first wires 140a
and 140b diverged by the first divergence roller 182, and a second
coupling roller 194 spaced apart from the first coupling roller 192
and disposed between the third pulley 166 and the drive unit 200 to
couple the pair of second wires 150a and 150b diverged by the
second divergence roller 184.
[0085] As shown in FIG. 4A, the pair of first wires 140a and 140b
are fixed to the first wire fixing portion 132, move along the
second link 120, and are diverged by the first divergence roller
182. The diverged wires 140a and 140b are wound around each of the
first pulley 162, the second pulley 164, the fourth pulleys 168a
and 168b, and the third pulley 166 in opposite directions to each
other, and are coupled again by the first coupling roller 192.
Then, the coupled wires 140a and 140b are fixed together to the
third wire fixing portion 212 of the drive unit 200.
[0086] As shown in FIG. 4B, the pair of second wires 150a and 150b
are fixed to the second wire fixing portion 134, move along the
second link 120, and are diverged by the second divergence roller
184. The diverged wires 150a and 150b are wound around each of the
first pulley 162, the second pulley 164, the fourth pulleys 168a
and 168b, and the third pulley 166 in opposite directions to each
other, and are coupled again by the second coupling roller 194.
Then, the coupled wires 150a and 150b are fixed together to the
fourth wire fixing portion 214 of the drive unit 200.
[0087] By providing a structure of diverging and coupling the
plural wires 140a, 140b, 150a, and 150b as described above, it may
be possible to eliminate torque disturbance occurring in the second
link 120 due to a difference in tensions applied to the pair of
first wires 140a and 140b and the pair of second wires 150a and
150b.
[0088] FIGS. 5A and 5B are diagrams for explaining a principle in
which a difference in tensions applied to the first wires and the
second wires is offset.
[0089] As shown in FIGS. 5A and 5B, when a difference .DELTA.T is
generated between a tension T applied to the pair of first wires
140a and 140b and a tension T+.DELTA.T applied to the pair of
second wires 150a and 150b, a force 2T applied in each of
directions P1 and P2 toward a center of rotation C1 of the first
pulley 162 by the pair of first wires 140a and 140b and a force
2T+2.DELTA.T applied in each of directions P1 and P2 toward a
center of rotation C1 of the first pulley 162 by the pair of second
wires 150a and 150b are applied to each of the fourth pulleys 168a
and 168b. Thus, the magnitude of the resultant force F1 applied to
the fourth pulley 168a of the fourth pulleys 168a and 168b is
2T+2T+2.DELTA.T, and the direction of the resultant force F1
applied thereto is a direction P1 toward the center of rotation C1
of the first pulley 162. In addition, the magnitude of the
resultant force F2 applied to fourth pulley 168b of the fourth
pulleys 168a and 168b is 2T+2T+2.DELTA.T, and the direction of the
resultant force F2 applied thereto is a direction P2 toward the
center of rotation C1 of the first pulley 162.
[0090] Since the fourth pulleys 168a and 168b are symmetrically
arranged with respect to the straight line L1 joining the center of
rotation C1 of the first pulley 162 and the center of rotation C2
of the second pulley 164 as described above in connection with
FIGS. 1 to 2B, an overlapping direction of the resultant force F1
applied to the fourth pulley 168a of the fourth pulleys 168a and
168b and the resultant force F2 applied to the fourth pulley 168b
of the fourth pulleys 168a and 168b is parallel with the straight
line L1 joining the center of rotation C1 of the first pulley 162
and the center of rotation C2 of the second pulley 164. Therefore,
the torque disturbance occurring in the second link 120 due to a
difference in tensions applied to the pair of first wires 140a and
140b and the pair of second wires 150a and 150b is offset, and
motion of the second link 120 may be more accurately
controlled.
[0091] Accordingly, unlike the link unit of the example of FIGS. 1
to 2B, the link unit of the example of FIGS. 4A and 4B includes the
pair of first wires 140a and 140b and the pair of second wires 150a
and 150b diverged in a partial section of the link unit.
[0092] While this disclosure includes specific examples, it will be
apparent to one of ordinary skill in the art that various changes
in form and details may be made in these examples without departing
from the spirit and scope of the claims and their equivalents.
Suitable results may be achieved if components in a described
device are combined in a different manner, and/or replaced or
supplemented by other components or their equivalents. Therefore,
the scope of the disclosure is defined not by the detailed
description, but by the claims and their equivalents, and all
variations within the scope of the claims and their equivalents are
to be construed as being included in the disclosure.
* * * * *